Piston having twisted skirt panels

Abstract

A piston assembly is disclosed herein. The piston assembly is integrally formed and unitary and is centered on a central longitudinal axis. The piston assembly includes a head with ring belt having a plurality of ring grooves. The piston assembly also includes first and second skirts, each having a top edge and a bottom edge being radially narrower than the top edge. The skirts also include first and second side edges. The piston assembly also includes first and second pin bosses spaced radially inward from the ring belt to define a short-pin support arrangement. The pin bosses include respective first and second pin bores axially aligned on a pin bore axis perpendicular to the central longitudinal axis. The piston assembly also includes a plurality of panels, each extending between one of the pin bosses and one of the skirts. Each of the panels include a top portion spaced closest to the head and bottom portion spaced furthest the head and a middle portion disposed substantially equally spaced from the top and bottom portions. Each of the panels twists along its length such that a ratio defined by a first distance between the top portion and a first plane perpendicular to the pin bore axis over a second distance between the bottom portion and the first plane increases along at least part of the length.

1. A piston assembly comprising:
 a head with an integrally formed and unitary ring belt having a plurality of ring grooves and centered on a central longitudinal axis; 
 first and second skirts integrally formed and unitary with said head and extending along said axis, each of said first and second skirts having a top edge adjacent said ring belt and a bottom edge spaced from said top edge along said axis and being circumferentially narrower than said top edge and first and second side edges; 
 first and second pin bosses integrally formed and unitary with said head and extending along said axis, said first and second pin bosses being minor images of one another across said axis and being spaced radially inward from said ring belt to define a short-pin support arrangement, and formed with respective first and second pin bores axially aligned on a pin bore axis perpendicular to said central longitudinal axis; and 
 a plurality of panels integrally formed and unitary with said head and each extending between one of said first and second pin bosses and one of said first and second skirts, said plurality of panels include a top portion spaced closest to said head and bottom portion spaced furthest from said head and a middle portion disposed substantially equally spaced from said top and bottom portions, and wherein each of said panels extends away from one of said pin bosses in a direction substantially perpendicular to a first plane containing both said central longitudinal axis and said pin bore axis over a length to merge with one of said skirts, and wherein each of said panels twists along said length such that a ratio defined by a first distance extending between said top portion of said panel and a second plane extending perpendicular to said first plane and containing said central longitudinal axis over a second distance extending between said bottom portion of said panel and said second plane increases along at least part of said length progressing from said pin bosses toward said skirts. 
 
     
     
       2. The piston assembly of  claim 1  wherein said first distance increases over at least part of said length and said second distance remains substantially constant over said length.